The research to be conducted will be essentially a continuation of certain aspects of the original grant proposal. In particular the calcium binding properties of the glycoprotein will be studied as these are possibly associated with the function of the clycoprotein in the renal tubule. In addition the remarkable aggregating properties will also be investigated with a view to determining the nature of the forces involved. The protein is known to contain approximately 30% carbohydrate and it would be of value to know if this plays a part in the self association process. The binding of calcium will be studied by equilibrium dialysis atomic absorption spectrometry and caldrimetry. It is hoped to determine binding constants and the Delta H of binding. These investigations will be correlated with the known changes in viscosity with variation of the calcium ion concentration. The relationship between calcium binding and protein-protein interactions will be studied and it is believed that the functional role of the the glycoprotein in the renal tubule may in this way be clarified.